Imides, hydrolysis reactions

Another alternative for preparing a primary amine from an alkyl halide is the Gabriel amine synthesis, which uses a phthalimide alkylation. An imide (—CONHCO—) is similar to a /3-keto ester in that the acidic N-H hydrogen is flanked by two carbonyl groups. Thus, imides are deprotonated by such bases as KOH, and the resultant anions are readily alkylated in a reaction similar to the acetoacetic ester synthesis (Section 22.7). Basic hydrolysis of the N-alkylated imide then yields a primary amine product. The imide hydrolysis step is analogous to the hydrolysis of an amide (Section 21.7). 

In this paper, we focus on the imide formation. Reaction mechanism for amide hydrolysis will be studied and presented in a separate paper. For cyclization to the imide, the three proposed routes (A, B and C in Scheme 1) correspond to different pH ranges [8]. Cyclization depends strongly on the acidity of the solution. It predominates under highly acidic conditions (hydrogen ion concertration < -1), this corresponds to Route A (l->2->3->6 and l->2 3->5->6), in which the intermediates are either pure cationic (l->2- 3 6) or a mixture of cationic and neutral (l->2->3->5->6). In the pH range 0-5, cyclization is not the dominant reaction. In Route B (l->4->5->6 and 1 5 6) where pH range is 0-2, the intermediates are zwitterionic or neutral. In Route C (l->7 8 9 6), the... 

The hydrolysis reactions are completely reversible, i.e. the hnal products of deamidation can interconvert through the cyclic imide... 

IR spectroscopy may be used to follow two reactions occurring in polyimides exposed to high temperatures and humidities hydrolysis of the imide linkages and hydrolysis of residual anhydride end groups. The hydrolytic susceptibilities of several polyimides were measured at 90°C/95% R.H. Polymers based on benzophenone tetracarboxylic acid dianhydride (with either oxydianiline or m-phenylene diamine) appeared to undergo rather rapid hydrolysis initially, but the reaction had essentially halted by the time the measured imide content had decreased by 5-6%. Polymers based on 3,3 ,4,4 -biphenyl tetracarboxylic acid dianhydride (with p-phenylene diamine) and pyromellitic dianhydride (with oxydianiline) showed no significant imide hydrolysis. In all the polymers, the anhydride was hydrolyzed quite readily. 

The results given above indicate that, despite some variations in rate, anhydride end groups can all be classed as quite readily hydrolyzed. In contrast, the hydrolytic susceptibility of imide linkages varies much more with the polymer examined. BPDA-PDA showed no measurable imide hydrolysis whatsoever. In PMDA-ODA the amount of hydrolysis observed was small enough that we cannot eliminate the possibility that impurities in the anhydride component, rather than PMDA itself, resulted in the formation of hydrolyzable material. Of the polymers studied here, only those that contained BTDA as the anhydride component showed a marked susceptibility to imide hydrolysis. Even in this case, the data suggest that the reaction is limited in that only about 6-7% of the imide linkages appear to be susceptible to hydrolysis. 

Activation of cross-linked agaroses with 1,1-carbonyl-di-imidazole yields a matrix for affinity chromatography devoid of additional charged groups/ The activated matrix (Scheme 7) is relatively stable to hydrolysis, but reacts smoothly with A-nucleophiles such as those present in affinity chromatography ligands and leashes. The matrix was treated with 1-aminobutane, 1,6-diamino-hexane, or 6-aminohexanoic acid and then with soybean trypsin inhibitor or 4-aminobenzamidine via a carbodi-imide-mediated reaction, and the products were shown to be useful for the affinity chromatographic purification of trypsin. 

The reaction of S2CI2 with gaseous ammonia in DMF at cu. -10 °C, followed by hydrolysis with cold dilute hydrochloric acid, is a standard preparation of these cyclic sulfur imides. The reaction of sodium azide with elemental sulfur in (Me2N)3PO is an excellent source of S7NH. The tetraimide 69 is prepared by reduction of S4N4 with methanolic SnCl2.2H20. 

The acidity values, ammonium ion contents and NH3 concentrations determined by the approaches described above were used to calculate the degree of hydrolysis of the aged polymer. This treatment assumes that ail the ammonium ion or ammonia arises solely from the primary hydrolysis reaction (i.e. the conversion of amide to carboxylate and accompanying ammonium ion). If, for example, some of the NH4 ion derives from the formation of imide linkages, then... 

Our interest in intramolecular imidization of PAm is for the many potential benefits of having the non-ionic, rigid closed ring structure in the molecular backbone. For example, imidization would lessen chain coiling. This report summarizes our recent study of molecular changes of PAm resulting from thermally promoted hydrolysis reactions. In particular, we will focus our discussion on reaction conditions involving intramolecular imide formation. 

In their subsequent report, Raymond et al. used the encapsulated gold complex, Au-Ga4L5, in combination with enzymes, esterases, or lipases in a one-pot tandem reaction sequence. Enzymatic ester/imide hydrolysis of allenic ester or amide results in an intermediate [27], which subsequently undergoes... 

Acidity of Amides, Imides, and Sulfonamides Characteristic Reactions Reaction with Water Hydrolysis Reaction with Alcohols Reactions with Ammonia and Amines Reaction of Acid Chiorides with Salts of Carboxylic Acids Interconversion of Functional Derivatives Reactions with Organometallic Compounds 18.10 Reduction... 

The reaction is applicable to the preparation of amines from amides of aliphatic aromatic, aryl-aliphatic and heterocyclic acids. A further example is given in Section IV,170 in connexion with the preparation of anthranilic acid from phthal-imide. It may be mentioned that for aliphatic monoamides containing more than eight carbon atoms aqueous alkaline hypohalite gives poor yields of the amines. Good results are obtained by treatment of the amide (C > 8) in methanol with sodium methoxide and bromine, followed by hydrolysis of the resulting N-alkyl methyl carbamate ... 

The imides, primaiy and secondary nitro compounds, oximes and sulphon amides of Solubility Group III are weakly acidic nitrogen compounds they cannot be titrated satisfactorily with a standard alkaU nor do they exhibit the reactions characteristic of phenols. The neutral nitrogen compounds of Solubility Group VII include tertiary nitro compounds amides (simple and substituted) derivatives of aldehydes and ketones (hydrazones, semlcarb-azones, ete.) nitriles nitroso, azo, hydrazo and other Intermediate reduction products of aromatic nitro compounds. All the above nitrogen compounds, and also the sulphonamides of Solubility Group VII, respond, with few exceptions, to the same classification reactions (reduction and hydrolysis) and hence will be considered together. 

When the reaction of S2CI2 with ammonia is carried out in a polar solvent, e.g., DMF, the hydrolysis of the reaction mixture with aqueous HCl produces a mixture of the cyclic sulfur imides S7NH, 1,3-, 1,4- and 1,5-S6(NH)2 and 1,3,5- and 1,3,6-S5(NH)3, which can be separated by chromatography on silica gel using CS2 as eluant (Section 6.2.1). °... 

Guareschi imides are useful synthetic intermediates. They are formed from a ketone reacting with two equivalents of the cyanoacetic esters and ammonia. This transformation is illustrated in the formation of 4,4-dimethylcyclopentenone 30.The synthesis was initiated with the Guareschi reaction of 3-pentanone 27 with 28 to generate imide 29. This product was hydrolyzed to the diacid and esterified. Cyclization of the diester via acyloin condensation followed by hydrolysis and dehydration afforded the desired target 30. 

Acidic hydrolysis of the amide group at pH 4.5 is a very slow reaction. Strong acidic conditions leads to a progressive insolubilization of the reaction product because of formation of cyclic imide structures ... 

---